1. Field of the Invention
The present invention relates to a roller assembly used for the image reading unit of a facsimile machine. More particularly, the present invention relates to a white roller assembly made of an extruded pipe.
2. Description of the Related Art
A fax ("facsimile") machine scans an original document, transmits an image of the document to a remote fax receiver, and reproduces the received image on a printer of the receiver. The image reading unit of a facsimile transmitter typically employs a contact image sensor (hereinafter referred to as "CIS") or a reduced optical system, thereby reading information on the original documents and converting them into electrical signals. Since the original document moves through the optical image reading path, the focus must be adjusted accurately in order to read out the sharpest possible image of the original documents. To guarantee such functions, such as the precision reading and accurate transportation of the optical image reading unit, a rubber roller (which can be a "white roller") is often employed, thereby precisely focusing on and accurately conveying the original documents. In the prior art, this rubber roller (which we may term "transportation roller") has a shaft running through the roller. This preference for a single shaft is expressly shown in the contemporary practice of image reading units of facsimile machines. On this matter, Morikawa et al. (U.S. Pat. No. 5,606,430, Image Reading Apparatus Having Projections On Surface Of Hopper Near Side Edges Of Paper Feed Path To Prevent Close Contact And Reduce Static Electricity, Feb. 25, 1997) discusses documents being sequentially taken out by a coaction of a paper feeding roller. Nishimiya et al. (U.S. Pat. No. 5,579,099, Document Conveying Device And Document Reading Device Operable Therewith, Nov. 26, 1996) discusses a document device for conveying a document in a reciprocating motion. Kohno (U.S. Pat. No. 5,552,902, Facsimile Apparatus With Internal Mechanisms For Conveying Originals And Recording Paper, Sep. 3, 1996) discusses reducing cost, size, and weight by reducing the number of motors. Park (U.S. Pat. No. 5,550,652, Automatic Document Feeder For A Facsimile Machine, Aug. 27, 1996) discusses automatic document feeding with a rotating shaft coupled to the ADF roller. Takahashi et al. (U.S. Pat. No. 5,325,213, Image Reader And Book Document Reader With A Page Turning Capability For An Image Forming Apparatus, Jun. 28, 1994) discusses page turning in an image reader for reading a book document laid on a document table in a spread position by optically scanning the surface of the document. Lee et al. (U.S. Pat. No. 5,278,677, Device For Removing Document Jamming Generated At A Transmitter Of A Facsimile Using A Contact Image Sensor, Jan. 11, 1994) discusses removing document jamming generated at a platen roller. From my study of the contemporary art and practice, I find that there is a need for roller assembly for an image reading unit of a facsimile machine that uses more than one shaft. This would give advantages, among others, of convenient manufacture.